The major objective of the proposed collaborative study is to determine whether a treatment regime involving long acting injectible fluphenazine decanoate is more effective than oral medication for schizophrenic patients. Although results of retrospective studies in England and elsewhere suggest that the long acting injectible medication can dramatically lower rehospitalization rates for such patients, a conprehensive prospective study examining variables other than relapse has never been conducted. Three kinds of effects will be examined; relief of psychopathological symptoms during two months of intensive treatment, averting re-emergence of symptoms and rehospitalization during one year maintenance phase and improvement of social perfor- mance during the maintenance phase. The study will also include determination of the cost of treatment for patients in terms of need for further intervention and support by mental health and other community institutions. Four treatment facilities following an identical protocol will increase the generalizability of results. The study will be coordinated by staff of the Psychopharmacology Research Branch. The significance of this study lies in both expected differences in efficacy between the two treatment regimes, and in the public im- plications of an improved system of treatment delivery for mentally ill individuals in community settings.